Two high-pressure superconducting phases in pressurized optical semiconductor GaP

Abstract Pressure engineering in semiconductors leads to a variety of novel physical phenomena and has recently received considerable attention. Here, we report on pressure-induced superconductivity in III–V gallium phosphide (GaP), a commercially important semiconductor that exhibits excellent optical performance. We show that the emergence of superconductivity is accompanied by the concurrence of piezochromic transition and metallization and can be correlated to a structural transition from the cubic to orthorhombic phase. In line with the structural origin of superconductivity, the critical temperature T _c monotonically decreases with increasing pressure up to ~50 GPa. Moreover, the superconductivity could be preserved toward ambient pressure because of the irreversibility of the structural transition. Nevertheless, the superconducting transition displays evident broadening associated with the presence of amorphization in the depressurized sample. The synchronous evolution of the structural and electronic properties not only shows a vivid structure-property relationship but also could facilitate the exploration of novel functionalities by means of pressure treatment.